Thread: thermal thoughts View Single Post
 01-27-2010, 03:57 PM #4 (permalink) Christ Moderate your Moderation.   Join Date: Nov 2008 Location: Troy, Pa. Posts: 8,919 Pasta - '96 Volkswagen Passat TDi 90 day: 45.22 mpg (US) Thanks: 1,369 Thanked 430 Times in 353 Posts If you want to negate the power loss, a simple valve in the intake tract will open the intake back to cold air, and within a split second, the ECM will react to the cold air, compensating with more fuel, creating more power. Gee, that was hard. I stand firm that any engineering thought that crosses anyone's mind should be filtered through normal, every day people first, before proceeding to think. Engineers have a tendency to work things out on paper, in 2 dimensions (metaphorically). Once you throw a square into the 3d world, it becomes a cube, and everything is changed. All of a sudden, your formulae just don't work anymore, and you're stuck back at square (cube?) 1. That said, the idea is a sound one, and there are engine builders working on engines with such things as dynamic compression in mind. Have been since the 70's, when 15:1 static was do-able in a gasoline ICE. Somewhere along the lines, people forgot what's already been done, and now subscribe to some nonsense which says that it can't be done, with no premise for the thought. Regarding the "less potential for expansion", this is just a ridiculous sentiment, when you consider that the percent change in temperature between 60 degrees to combustion temp and 140 degrees to combustion temp is very small. Without looking it up, imagine for a second that cylinder combustion temps are approx 1,000degF. The difference between 60degF and 1,000degF is 940degF. The difference between 140degF and 1,000degF is 860degF, or a total change of 80degF between the two (not counting changes in combustion temps due to the hotter air). 80degF is 8% of 1,000degF... so what noticeable effect is 8% expansion going to have? Of course, if you count differences in pressure because of lessened combustion gasses, etc... the number increases some. It's still not going to make a huge difference. __________________ "¿ʞɐǝɹɟ ɐ ǝɹ,noʎ uǝɥʍ 'ʇı ʇ,usı 'ʎlǝuol s,ʇı" Last edited by Christ; 01-28-2010 at 12:29 AM..